Application of a Liquid Chromatograph Coupled with a Flameless Atomic Absorption Detector for Speciation of Trace Organometallic Compounds

Abstract

Use of a commercial flameless (graphite furnace) atomic absorption detector (QFAA) automatically coupled to a high-pressure liquid chromatograph (HPLC) was demonstrated to provide element-specific separation and detection of organometallic compounds at nanogram concentrations in both protic and nonpolar solvents using conventional columns. Relative sensitivities of the HPLC-GFAA system for compounds of arsenic, lead, mercury, and tin were shown to be mainly functions of LC flow rate and relative AA sensitivity for each element. Separation of mixtures of organometal ions required both isochratic and gradient elution on reverse phase columns, but incorporation of certain charged or neutral ligand concentrations was necessary for achieving complete resolution of different organometal species. The QFAA detector can be operated in either a rapid sampling mode, providing higher resolution of the HPLC effluent, or in a batch survey mode which permits, with only slight (5–10%) loss of effluent, recovery of sample fractions for additional analyses. KEY WORDS: Arsenic, element-specific detector, flameless atomic absorption, flow monitoring, high-pressure liquid chromatography, lead, ligand, mercury, nanogram sensitivity, organometallic compounds, speciation, tin.